STABLE TREMOLO SYSTEM FOR STRINGED MUSICAL INSTRUMENTS AND RELATED ADJUSTMENT DEVICE

Abstract: The invention consists into a tremolo-bridge for stringed instruments, in which the "bridge" and the "tailpiece" can rotate synchronously on one of two fulcrums, depending on the driving direction of the tremolo arm. Only a fulcrum at a time is involved during operation, and they represent the only points of friction. The best way of accomplishing this, is to build the unit by two blocks, each one having its own rotation axis. One block has to work as bridge and tailpiece solidly. This block can turn directly on one of the fulcrums, and indirectly on the other one, the other block working as a connection. For best adjustment, two sets of countertension springs are provided (one for each block), and also a special adj. device. The main feature of the system is its adjustable range of stability, in which it is indifferent to the variations of the strings pull (due to the fact that it doesn't work in a critical balance position). It shows exact tune keeping and come back to the rest position. Other features are: simplified tuning of the instrument, increased sustain, never falling down strings action. There are no restrictions to the shape of the system, and it can be embodied as replacement for common tremolos.

Description: STABLE TREMOLO SYSTEM FOR STRINGED MUSICAL INSTRUMENTS AND RELATED ADJUSTMENT DEVICE. The present invention relates to a tremolo-bridge system for stringed instruments provided with good stability features and a special adjustment mechanism. The TREMOLO effect consists into a pitch variation of the notes produced by the instrument. Starting by now we will refere in the examples to the solid body electric guitar, and will use the definition "guitar body" to refer at the body itself or at any structure which is solid with it. Furthermore we will use the term "fulcrum" to indicate the support points of the rotation axes. The figures 1, 2 and 3 are relative to the state of the art, the ones from 4 to 8 express the operating principles of the proposed system, and the ones from 9 to 14 represent an accomplishing solution, in conformity with an accomplished prototype. State of the art The current tremolo systems are constituted with a unique block which holds up the saddles on where pass the strings, the anchor points of the strings, the control arm and possible additional devices, which here are not considered. All the block is "floating" on a fulcrum in a balance position between the tension of the strings and that of one or more countertension springs. The fulcrum is usually constituted by two or more screws or pivots fixed to the guitar body. In fig. 1 the device is specified by the "V" letter and is shown in plan view; P are the pivots, S the strings saddles, FC the strings passing holes, L the control arm, C the strings, G the guitar body. The other parts shown do not concern the tremolo. Fig. 2 is a side view which evidences the development in height of the system and how it is "floating" ; M are the countertension springs, SF is the ending ball of each string, CV is the cavity obtained in the guitar body and CO is its cover plate. Fig. 3 is a bottom view with the CO cover removed. The holes FC pass vertically through the block, and have the terminal lower part of bigger diameter so to receive the ending balls of the strings (see FC in figures 1 2 and 3). Such systems are driven by a force applied by the hand to the control arm. The force alters the balance and changes the strings tension with subsequent variation of the produced notes. The force can be applied in two directions (see figure 2)': direction B, which we will call descending, which loosens the strings tension and gives flat notes; direction A, which we will call ascending, which increases the strings tension and gives sharp notes. Such systems present the following problems: the tension variation of a string, for example during the tuning phase, alterates the balance and affects inversely the other strings; some playing musical techniques give out "out of tune" notes; -part of the force applied to the strings (by the player) to make them vibrate is wasted on the springs; the transmission of the vibrations to the guitar body is reduced by the fact that the system is "floating" and has a mechanical coupling with the instrvunent entrusted only to the fulcrum; the total resonance, the timbre characteristics and the sound sustain are penalized. There have been conceived systems which overcome some of these problems, but give some others as realizing complexity, set up difficulties, instability, worsening of the acustics versus a gain in the stability, and viceversa. Some systems need a specific blocking action during the use. Others, when operated to the ascending direction, pull the strings making them slide on the saddles; in this way, over to add friction and noise, they damp a part of the vibrating string, with a loss of sound sustain and harmonics; furthermore, for their own nature, these systems cannot be equipped with locking saddles (that is having the anchor point of the string), neither with any kind of fine tuning mechanism. In the following is described a system which overcomes these problems without important collateral inconveniences. The proposed system The proposed system is not a floating type, and is constituted by two separate blocks which turn on different fulcrums. Such fulcrums can , at the farest, be coaxial. We will call these two blocks "main block" and "secondary block", even if they have functions of the same importance. (figure 4 = exploded view, figure 5 = assembled view, figures 6 7 and 8 = side views in three operating positions). The MAIN BLOCK BP turns on a fulcrum immovable towards the guitar body. Such fulcrum is solid to the guitar body (pivot posts PP ) . This block does not hold up the saddles for the strings, neither any anchor point for the strings, nor the mounting point of the control arm (figure 4). It is kept normally in flat position on the guitar body by convenient countertension springs M (fig. 6). For flat position is meant that of maximum possible rotation towards the direction A until the contact with the guitar body. This position represents the rest position of the main block. From this position, it can rotate only in direction B -descending- (fig. 7). The SECONDARY BLOCK BS works at the same time as "bridge" (saddles) and "tailpiece" (strings anchorage). It turns on a fulcrum which may be placed on the main block. In this example (fig. 4) the fulcrum is constituted by the pivots PS, which have a threaded part that winds into the threaded holes FF on the main block, and a non-threaded part that enters into the holes FN of the secondary block. This block (see fig. 4) holds up the saddles S for the strings, the anchor points for them (holes FC) , eventual additional mechanisms (here not considered), and the mounting point of the control arm L. Has to be noticed, in particular, that the saddles rotate solidly with the secondary block, with the anchor points of the strings, and with the control arm. This can allow the use of locking saddles, which lock the strings, and in this case a distinct tailpiece section may be redundant and so eliminated (depending on the type of locking saddles). The strings tension, applied to the secondary block through the saddles and the anchor points, tends to make it rotate toward the direction B (descending), while the main block stays on the rest position because of the springs. One or more stops, placed on the main block, stop the rotation of the secondary block in its rest position (in figs from 4 to 8 the stops are the items FA) . The secondary block can rotate by itself on its own fulcrum towards the A direction (ascending - fig. 8), and towards the B direction (descending - fig. 7) along with the main block around the relative fulcrum. We notice that the control arm is applied to the secondary block. The entire system is on the rest position when both the blocks are on the rest position, and that is when the main block is arrested on the guitar body, due to the springs traction, and the secondary block is arrested by the stops on the main block, due to the strings pull (fig. 6 ). When the arm is driven towards the B direction (descending) both the blocks move; when it is driven toward the A direction (ascending) only the secondary block moves. When the arm is released, however, the system comes back to the rest position. The pulling force of the countertension springs must be greater than the minimum one necessary to keep the main block in contact with the guitar body when the strings are in tune. Of how much must be greater is a constructive choice, depending from this the stability range of the system and its handyness. We explain the concept of stability range: said Tl the total tractive force of the strings, a force T2 > Tl to which the main block detaches from the guitar body exists; the difference T2-T1 represents the stability range. The following has to be noticed : -in absence of the strings, the secondary block is free to move. - if a string (or more than one) breaks, the entire system does not move. - if playing techniques as "bending" are used (shifting of the strings using the fingers on the guitar fretboard) , the entire system does not move, within the stability range. -there is a better transmission of the sound to the guitar body, because the system is not floating, even it can be operated either in descending or ascending direction. - There is no wasting of the force applied to the strings to make them vibrate. - There are no frictions, but on the fulcrums; it has to be noticed that only one fulcrum at a time is interested during the operation. - the tuning is simplified. Explained the operating principle, we are going to explain some considerations about construction, expecially to introduce the understanding of the differential adjustment mechanism which will be shown later. Standing that the device, as it has been described, works, during the testing of prototypes a certain driving hardness towards the B direction (ascending) has been noticed. This is due to the fact that must be won, by driving the arm, all of the strings traction. Towards the A direction (descending) , instead, the requested force can be set by springs adjustment, even with effect on the stability range. Considering that the tension of tuned strings is constant, and chosen the tractive force of the countertension springs, we thought to share this force between the two blocks in a differential way, so to facilitate the driving towards the direction A (ascending). Two sets of springs have been used: one anchored to the main block and the other to the secondary block. We will talk about it in detail during the explanation of the next figures. For reasons of compatibility with the currently used systems, we propose the accomplishing solution of fig. 9 and following. Fig. 9 shows an exploded view in conformity with a realized prototype. In it can be seen: -The saddles S, of common type. They have to be mounted into the holes HS on the secondary block. - The control arm L, of common type. It has to be mounted into the hole FL on the secondary block. - The secondary block BS. It is constituted by a unique block of metal or by parts however joined together. The secondary block holds up the holes HS for saddles mounting, the threaded hole FL for arm mounting, the holes FC for strings passing, the non-threaded holes FN for the pivots PS which represent the fulcrum for this block, and in the lower part the holes FS for springs hooking. - The main block BP. It is constituited by a unique block of metal or by parts however joined together. It has two knife-edge shaped notches, which go to rest onto the pivot posts PP, which represent the fulcrum for this block. The bar FA constitutes the stop for the secondary block (see better in the figure 12). The threaded holes FF hold up the pivots PS. Into the lower part it has the holes for springs hooking. - Two pivot posts PP. Have to be fixed (screwed) to the guitar body. - Two pivots PS. - Two springs MP for the main block, and two springs MS for the secondary block. - The differential adjustment device DR, as later described, constituited by the parts shown in figure 14, where even the springs are shown again. Fig. 10 shows the system assembled and mounted on the guitar body; fig. 11 shows a side view of the system on the rest position; fig. 12 shows a section of the two blocks that goes through the hole FC more close to the control arm L; fig. 13 shows a bottom view, with particular evidence to the adjustment device; fig. 14 shows the component parts of such device. The adjustment device is seen assembled in figs 11 (side) and 13 (bottom), and in exploded view in fig. 9. Its parts are (figure 14): - Screws VI; have to be screwed into the guitar body. -Plate PI; it has two non threaded passing-through holes FI for the screws VI, and a non threaded passing-through hole F2 for the screw VR. - Plate P2; it has two holes KS for the hooking of the springs MS and a hole F3 with left-handed thread for the part of the screw VR having wider diameter. - Plate P3; has two holes KP for the hooking of the springs MP and a hole F4 having a right-handed thread for the part of the screw VR having smaller diameter. - Adjustment screw VR; is constituted by two parts having different diameters and counter-handed threads; the part having wider diameter has left-handed thread, and that having smaller diameter has right-handed thread (or viceversa, unless to invert the threads of the holes F3 and F4). - The springs MP; have to be hooked to the main block and to the plate P3. - The springs MS; have to be hooked to the secondary block and to the plate P2. The total tension of the springs depends on how much the screws VI are screwed in (figs 11 and 13). By winding the screw VR, the plates P2 and P3 shift in opposite directions, adjusting in a differential way the distribution of the total traction onto the two blocks (within a satisfying utilization range) . The length of the screws VI and VR, the pitch of the threads of VR, the length, the number and the springiness of the springs and the anchor points have to be chosen for constructive factors. We precise that however the minimum number of springs necessary to the main block is 1 (one), and to the secondary block is 0 (zero). The application of other springs and of the differential adjustment device is an optimization. It has to be noticed that an adjust of the system so that it works "floating" is possible. For constuctive factors and for the desired range of the tremolo effect, instead, the shapes of the two blocks and the two rotation axes (fulcrums) have to be chosen. In particular, are possible accomplishings having one or both the rotation axes inside the guitar body. The constructive solutions are various. A proper arrangement of the rotation axes (see figs from 9 to 12) gives the system another important feature: the minimum distance between the strings and the instrument fretboard corresponds to that of the rest position. This is important when transducers have to be used that need to be mounted close to the strings as much as possible, such as transducers for "MIDI" converters.

Claims: C L A I M S 1. Tremolo-bridge system for stringed instruments, in which the "bridge" can rotate, directly or indirectly, on ONE OF TWO rotation axes, depending on the driving direction (ascending or descending) of the tremolo arm. 2. Tremolo-bridge system, as described in the preceding claim, constituted by two interacting blocks (conventionally called "main" and "secondary"), each one having its own rotation axis and its own set of springs which provide countertension to the strings pull. 3. Tremolo-bridge system, as described in the preceding claims, in which the secondary block works, in a solid and synchronous way, as "bridge" and "tailpiece". 4. Tremolo-bridge system, as described in the preceding claims, in which the "bridge", when driven by the tremolo arm, starting from the rest position can rotate as follows: - on the rotation axis of the main block; in this case the main block works as a connection and follows the bridge motion; - on the rotation axis of the secondary block; in this case only the secondary block, with which the bridge is solid, moves. 5. Tremolo-bridge system, as described in the preceding claims, in which the system, when not operated, stays on a well defined "non floating" rest position, not affected by limited variations of the total strings pull: the combined action of springs and strings stops the main block on the instrument body and the secondary block on some stop on the main block. 6. Tremolo-bridge system, as described in the preceding claims, provided with an adjustment mechanism based on the following: - one or more common screws (tipically two) used to set up the total springs tension; they are more or less screwed into the instrument body, and retain a plate which holds up the head of a special screw; - a special screw, which has two opposite-threaded sections; each section drives a related plate to which is hooked a set of springs coming from a block; such screw, when winded, shifts in opposite directions the two plates; this allows to share out, in a differential way, the total springs tension to the blocks, while keeping it unchanged (within a reasonable usable range) . 7. Tremolo-bridge system, as described in the claim no. 6, in which the adjustment mechanism is not essential for the system to work: the minimum number of springs for each block is zero, but at least one block has to have at least one spring. 8. Tremolo-bridge system, as described in the preceding claims, in which the friction can be limited to the fulcrums, and only a fulcrum at a time is involved in the running.

Inventors: IOVANE ANTONIO, IOVANE, ANTONIO
Applicants: IOVANE ANTONIO, IOVANE, ANTONIO
Application year: 1994
Main classification: G10D3
IPC codes: G10D3